Learn how to make Beef Japchae, a well-known Korean glassy noodle stir fry! It's a delicious stir fry with sweet potato starch noodles, vegetables, and beef. It's easy to prepare ahead of time for a quick weeknight supper or potlucks. If not allergic to sesame, garnish with a sprinkle of toasted sesame seeds.
Pat dry steak with a paper towel, place the steak in a freezer bag, and freeze for 30 minutes to firm it up.
Boil water in a large pot (1/2 to 2/3 full) and blanch spinach for 30 seconds. Use a slotted spoon to take the spinach out of the hot water and rinse under cold running water in a colander. Gently squeeze out excess water and transfer to a small bowl, add 1 teaspoon sesame oil, a pinch of salt, mix and set aside.
Season to taste with additional soy sauce and drizzle with 1 teaspoon sesame oil, garnish with the rest of the scallions, and sesame seeds if using.
Serve as a main entree by itself or as a side dish.